To ban question on question & answer site (because it have more than one answer) is a bit weird solution, which I also disagree, because there is many ways around of it.
Instead of changing question to be about controversy it is also possible to just outline controversy in the answer.
Or, answer could state that it presents just one point of view. Or, it maybe be enough if a commentary to such answer could state that it's just one point of view, without beginning dispute about it. One commentary to state that there exists another point of view is not yet dispute and should be allowed.
What is actually bad in 'controversy' is disrespect to other tradition. It is not "controversial" when answers present some "non-controversial" subject from different points of view (w/o even acknowledge of existence of other points of view). It's only become offensive when there is 'only this is true' attitude (idealism) and derogation of other views (cynicism). So I believe what is actually need to be changed is just removal of disrespectful statements. Only disrespect need to be removed, and not different views.
Like someone say, "mahayana developed pseudo-sutras" - there "pseudo" is disrespectful and biased.
Or, "abuse by generations of abhidharmists" - it may have take-it-easy attitude and be funny to the author, but this is disrespect to the abhidharmic tradition.
It's may be normal in dispute if opponents pinch each other a bit, but in answer, which is not supposed to start a debate, such pinching is not needed.
So, in summary, instead of deleting questions, or asking to rephrase, or to make obligatory survey in the answer, I propose to delete derogatory statements only and allow single commentary to state existence of other point of view, and leave everything else as it is.